Apparatus for handling granular material



Nov. 10, 1953 FERNALD 2,658,603

APPARATUS FOR HANDLING GRANULAR MATERIAL \Filed Jan. 28, 1950 Patented Nov. 10, 1 953 APPARATUS, F r, H

Russell G.- Fernald, Down to Western Electric LING GRANULAR MATERIAL ers Grove, 111.; assignor ompany, Incorporated,

New York, N. Y; a corpora'tion'o'f New York Ap lication Jammy 28, 1 50. Serial N 141,145.

9 Glaims. 1

This invention relates to methods of and an paratus for handling granular materials and more particularly to a method of and apparatus for constructing the inner surfaces of granular material receiving or handling equipment.

1 In the handling ar d transfer of many granu lar materials, it is necessary or desirable that the materials be in a mere or less moist condition, either for reasons necessitated by their ultimate use or for handling reasons. In foundries, for example, molding sand which is to be used to form a mold must be slightly damp in order that proper adherence be maintained in the mold, and in mechanized foundries where molding sand is automatically conveyed to hoppers or other receiving bins at molding stations, such sand is conveyed between and transferred from the various components of the foundry system while in a relatively moist condition. In the past, all of the transfer bins; hoppers, aerators and most other equipment with which the sand comes in contact have been of metallic construction and, as a consequence thereof, an appreciable amount of sand has a tendency to adhere to such metallic surfaces. Such adherence of the sand to the metallic surfaces results in many undesirable effects tending to reduce the efficiency of the equipment. In the first place, the equipment tends to become clogged and consequently the volume of sand transferred decreases. In the second place, sand adhering to the sides of the equipment tends to dry out and then fall back into and mix with the properly moistened sand. The latter action results in molds of poor texture and frequently results in poor castings. Nu merous other disadvantages resulting from sand or other granular materials adhering to such surfaces are apparent; however, it is believed that, with respect to sand molding, the two mentioned above are the most important. 7

It i an object of this invention to facilitate the handling ofsand or the like granular materials by eliminating the tendency of the granular material to adhere to surfaces with which it comes in contact.

In accordance with one embodiment of the invention, a method of andapparatus for eliminating adherence of granular materials to surfaces may comprise providing such surfaces with liners consisting of an elastic and compressible material such as freely flexible rubber or the like material. Ordinarily; in the case of a surface at an angle to the horizontal and over which granular material "flows; such a liner may be secured to the surface at its topedgeandfreely 2 suspended so as to assume a normal position either in contact with or in close proximity to the surface to which the sand tends to adhere. Thus it W11 be seen that any sand or other gra ular material coming in contact with the rubber liner and adhering thereto will set up unbalancing forces in thefiexible liner tending to distort it. The distortion, in turn, tends to cause the bond to be broken between the liner and the adhering material, thereby allowing the material to continue its progress. It has been found that such bonds are caused to be broken by two sepa-v rate forces which are set up in the liner by ad,- herence of material thereto. One of the forces is exerted due to'the actual stretching of the liner and the other and more important force ex erted due to the actual compression or expansion of the liner due to the forces exerted sub stantially normal to the surface of the liner by the weight of the material adhering thereto. Whether the normal force is one of compression or expansion depends upon the orientation of the liner, as will be more fully explained hereinafter.

A more complete understanding of the invention may be had by referring to the following detailed description of one embodiment of the invention whieh is illustrated in the accompanying drawing wherein:

1 i a schem c diagram of a pa f he sand handling apparatus used in a foundry;

Fig. 2 i an isometric View of a molders hop- D Fig 3 is a top plan iew of the molders hop-i per shown in Fig. 2; and

Fig. 4 is an enlarged view in cross section showing the details of construction of one of the four corners of the molders hopper.

It is to be noted thatalthough the invention has been illustrated and will be described with reference to the handling of molding sand in a foundry, the invention is capable ofbeing used in conjunction with the handling of any other granular materials. For example, the inyention may be used to advantage in' conjunction with the handling of pulverized coal wherein it is necessary to moisten the coal in order to reduce the amount of dust'resul illg' from its handling. The invention may also be employed in handling other granular materials such as sugar, salt, et cetera,

Referring to Fig. 1 of the drawing, a collecting belt conveyor It] serves to transport moist mold} ing sand from a muller (not shown) and th sana is then dumped into a chute ll, wherein it travel by gravity until it is deposited in a vertical bucket conveyor l2. A bin l5 may also be provided to catch any of the sand flowing through the chute I that is not picked up by the buckets on the bucket conveyor l2. Since the sand being carried by the collecting belt conveyor I0 is in a relatively moist state, the sand gravitating over the lower side of the chute H, as well as along the vertical side thereof, has a tendency to adhere to the surfaces thus contacted by the sand. This condition is, of course, undesirable since it has a tendency to impede the free flow of moving sand through the chute II. In order to obviate this condition, sheets I3 of rubber or the like material may be provided along the bottom and side walls of the chute H and these sheets l3 may be secured in overlapping relationship with the walls of the chute H by means of holding strips I4, which may be of any suitable material, such as hard rubber or metal.

After passing through the chute H, the molding sand is transported upward by the bucket conveyor l2, where it is deposited in a chute positioned with its exit above an aerator 2|. The chute 20 may, likewise, be provided with sheets 22 of rubber or the like material overlapping those portions of the chute 20 with which the sand comes in contact. Suitable holding strips 23 may also be employed to secure the sheets 22 within the chute 20. Sand passing through the exit of the chute 20 and falling into the aerator 2| is finely dispersed as it is ejected from the aerator. The finely dispersed sand is impinged on various inner surfaces of a casing 24, which surrounds the aerator 2| and the impinging sand has a tendency to adhere to the inner surfaces of the casing 24 and thereby impede the free flow of sand in the system. To reduce the amount of sand thus adherin to the inner surfaces of the casing 24, various designs of rubber sheets may be employed. One portion of the inner surface of the aerator casing 24 has an arcuate configuration and since this portion is at the position where the majority of the aerated sand impinges, a sheet 25 of rubber or the like material may be provided along the inner arcuate surface. The sheet 25 is secured at both ends by holding strips 26 and 21. Thus it is obvious that the bond formed between the sheet 25 and any sand impinging thereon will be broken by virtue of the weight of the sand acting in a direction substantially normal to the surface of the sheet to cause a physical deformation thereof. The sheet 25 may also be provided with a loosely hangin extension 28, which also serves to prevent sand from sticking to the casing 24. It is obvious, of course, that in the case of the extension 28, the weight of the sand adhering thereto causes an actual stretching of the extension 28 in a direction longitudinal therewith. This stretching is also effective to rupture the bond existing between the sand and the extension 28. Another sheet 29 having holding strips 30 may also be provided within the aerator casing 24 and the function of the sheet 29 is the same as the function of sheets l3 and 22.

The aerated sand is picked up by a belt conveyor 40 on which it is transported to positions above a plurality of molders hoppers 4 I, only one of which is shown. The sand is deflected from the conveyor 40 into the molders hoppers by means of plows 42, and the sand may then be released from the hoppers 4| when needed by manual operation of a handle 43, which controls a gate 44.

The construction of the molders hopper 4| is shown in detail in Figs. 2, 3 and 4. As is evident from reference to Fig. 3, the molders hopper 4| is so fabricated that it has two sloping sides 50 and 5| and two substantially vertical sides 52 and 53, and the four sides thereof converge to form a reduced exit 54. Since the gate 44 is only open when sand is desired by the operator, it will be apparent that sand will, at times, be stationary within the hopper 4|. Since the sand is still in a moist condition, the fact that its movement is not continuous increases its tendency to ad here to the interior surfaces of the hopper 4|. For this reason, sheets 60 of rubber or the like material are suspended in overlapping relation with each of the sides of the hopper 4|. The sheets 60 are fabricated into a complete lining for the hopper by providing rubber corner strips 6|, which are vulcanized to the vertical edges of the sheets 60. Since it is undesirable to allow any sand to accumulate behind the liner thus formed, suitable filler material 62 may be provided at each corner between the edges of the sheets 60 and between the corner strips 6| and the hopper 4|. The filler material 62 need not extend the complete height of the hopper, but may extend only a few inches downward from the top of the hopper. The liner thus formed by the sheets 60, corner strips 6| and filler material 62 may then be secured to the molders hopper by means of holding strips 63, which are preferably strips of a suitable metal of sufiicient strength to support the weight of the liner.

It will be seen, therefore, that in all cases where granular materials have a tendency to adhere to surfaces over which they are flowing either by gravity or otherwise, such adherence may be prevented by providing liners of relatively soft pliable rubber or like material over the surfaces. It will be further seen that any material adhering to such rubber liners tends to distort the liner to such an extent that the bond between the liner and the adhering material is effectively broken. In the case of granular material adhering to a liner in such a manner that a component of the weight of the material is in a direction substantially normal to the plane of the liner, the actual compression or expansion of the liner caused by the normal component of weight of the material adhering thereto causes the bond to be broken. In addition to the component of weight normal to the plane of the liner, a second component of the weight of the material parallel to the plane of the liner also causes the liner to be stretched longitudinally to thereby further assist in the breaking of the bond between the material and the liner. In the case of a vertical liner, the weight of the material has no component perpendicular to the surface of the liner and the bond between the material and the liner is broken only by virtue of the longitudinal stretching of the liner.

. Any relatively flexible, commercially available elastic and compressible material such as rubber or the like may be employed as liner material, and the thickness of the rubber liner may be varied according to the conditions encountered. For example, commercially available relatively soft pliable sheet rubber of a thickness of approximately A; inch may be advantageously employed.

It is to be understood that the above-described arrangements are simply illustrativ of the application of the principles of the invention. Numerous other arrangements may be readily devised by those skilled in theart which will embody the principles of the invention and fall within the spirit and scope thereof.

What is claimed is:

In qu pment for handlin moistened granular material having chutes into which the material is dumped for movement therethrough, flexible elastic and compressible liners suspended at their upper edges only within the chutes in overlapping relationship with the inner surfaces of said chutes, the weight of the material adhering to said liners being effective to stretch and distort said liners to maintain their surfaces clean of said material.

2. An apparatus for handling moistened gran ular material, which comprises a guiding element composed of inelastic material, a curtain composed of elastic compressible material disposed in a position covering the guiding element, exclusive means suspending the curtain in said position relative to the guiding element, said ourtain-suspending means serving to permit at least the portion of the curtain from one end thereof to the central portion thereof hang free with respect to the guiding element, and means for advancing moistened granular material past the element and curtain.

3. An apparatus for handling moistened granular material, which comprises a conduit having an entrance end and an exit end through which moistened granular material may be advanced, a liner composed of elastic material extending generally along the conduit, and exclusive means securing an end portion of the liner in a position in which the unsecured portion of the liner extends toward the exit end of the conduit, whereby the portion of the liner beyond the securing means is free to stretch and compress to dislodge granular material stuck thereto.

4. An apparatus for handling moistened granular material, which comprises a conduit having an entrance end and an exit end through which moistened granular material may be advanced, a sheet composed of elastic material extending generally along the conduit, and exclusive mounting means securing against movement relative to the conduit only portions of the sheet spaced substantially from the end thereof nearer to the exit end of the conduit, whereby the portion of the sheet etxending beyond the mounting means toward the exit end of the conduit is free to stretch and compress to dislodge granular material stuck thereto.

5. An apparatus for handling moistened granular material, which comprises a hopper disposed vertically, a generally tubular liner designed to fit loosely into the hopper, said liner being composed of compressible elastic material, and exelusive liner-mountin means fastening only the upper portion of the liner against movement relative to the hopper and maintaining the lower portion of the liner free so that the liner may be stretched by granular material stuck thereto to dislodge the granular material.

6. An apparatus for handling moistened granular material, which comprises a hopper disposed vertically and having a predetermined taper, a generally tubular liner designed to fit into the hopper and having a greater taper than the hopper, said liner being composed of compressible elastic material, and exclusive fastening means securing only the upper portion of the liner against movement relative to the hopper.

7. An apparatus for handling moistened granular material, which comprises a hopper disposed. vertically and having a predetermined taper, a generally tubular liner designed to fit into the hopper and having a greater taper than the hopper, said liner being composed of compressible elastic material, and exclusive linermounting means fastening only the upper portion of the liner to the hopper and including bars pressing the upper portion of the liner against the hopper.

8. An apparatus for handling moistened granular material, which comprises a generally vertically extending hopper of generally rectangular shape in transverse cross-section and tapering from a predetermined cross-sectional area at the top thereof to a smaller cross-sectional area at the bottom thereof, a liner generally similar in shape to the hopper and composed substantially of compressible, elastic material, said liner having reinforced corner portions, and exclusive liner-fastening means securing only the upper end of the liner to the hopper, said liner tapering from top to bottom more sharply than the hopper so that the lower portion of the liner is spaced from the hopper.

9. An apparatus for handling moistened granular material, which comprises a conduit having an entrance end and an exit end through which moistened granular material may be advanced, a tubular liner composed of elastic material extending generally along the conduit, said liner having laterally spaced portions extending therealong which have different elasticity from that of the portions of the liner therebetween, and exclusive liner-mounting means securing only the end portion of the liner nearest the entrance end of the conduit to the conduit, whereby the portion of the liner beyond the liner-mounting means is free to stretch and compress to dis lodge granular material stuck thereto.

RUSSELL G. FERNALD.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,438,996 Grifiin Dec. 19, 1922 1,570,795 Tainton Jan. 26, 1926 2,214,533 Fave Sept. 10, 1940 

